DTC Troubleshooting
DTC Troubleshooting: P0141, P0161
DTC P0141:
Rear Secondary HO2S (Bank 1, Sensor 2) Heater Circuit Malfunction
DTC P0161:
Front Secondary HO2S (Bank 2, Sensor 2) Heater Circuit Malfunction
NOTE:
- Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information Initial Inspection and Diagnostic Overview.
- Information marked with an asterisk (*) applies to the front bank (Bank 2).
1. Turn the ignition switch to ON (II).
2. Clear the DTC with the HDS.
3. Start the engine.
4. Check for Pending or Confirmed DTCs with the HDS.
Is DTC P0141 and/or P0161* indicated?
YES -
Go to step 5.
NO -
Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at secondary HO2S (Sensor 2), the PGM-FI subrelay (LAF), the driver's under-dash fuse/relay box, and the PCM.�
5. Turn the ignition switch to LOCK (0).
6. Check these fuses:
- No. 19 OPTION 1 (30 A) fuse in the under-hood fuse/relay box.
- No. 4 LAF (A/F SENSOR) (15 A) fuse in the driver's under-dash fuse/relay box.
- No. 23 IGP (7.5 A) fuse in the under-dash fuse/relay box.
Are any of the fuses blown?
YES -
Repair short in the wire between secondary HO2S (Sensor 2), the PGM-FI subrelay (LAF), and the fuse(s), then go to step 22.
NO -
Go to step 7.
7. Disconnect the secondary HO2S (Sensor 2) 4P connector.
8. At the sensor side, measure the resistance between secondary HO2S (Sensor 2) 4P connector terminals No. 3 and No. 4.
Is there 5.4-6.6 Ohms at room temperature?
YES -
Go to step 9.
NO -
Go to step 21.
9. At the sensor side, check for continuity between body ground and secondary HO2S (Sensor 2) 4P connector terminals No. 3 and No. 4 individually.
Is there continuity?
YES -
Go to step 21.
NO -
Go to step 10.
10. Jump the SCS line with the HDS.
11. Disconnect PCM connector C (49P).
12. Check for continuity between PCM connector terminal C5 (C7)* and body ground.
Is there continuity?
YES -
Repair short in the wire between the PCM(C5 (C7)*) and secondary HO2S (Sensor 2), then go to step 22.
NO -
Go to step 13.
13. Check for continuity between PCM secondary HO2S (Sensor 2) 4P connector terminal No. 3 and PCM connector terminal C5 (C7)*.
Is there continuity?
YES -
Go to step 14.
NO -
Repair open in the wire between the PCM(C5 (C7)*) and secondary HO2S (Sensor 2), then go to step 22.
14. Remove the PGM-FI subrelay (LAF) (A).
15. Connect secondary HO2S (Sensor 2) 4P connector terminal No. 4 to body ground with a jumper wire.
16. Check for continuity between PGM-FI subrelay (LAF) 4P connector terminal No. 2 and body ground.
Is there continuity?
YES -
Go to step 17.
NO -
Repair open in the wire between secondary HO2S (Sensor 2) and the PGM-FI subrelay (LAF), then go to step 22.
17. Disconnect PCM connector A (49P).
18. Connect PGM-FI subrelay (LAF) 4P connector terminal No. 3 to body ground with a jumper wire.
19. Check for continuity between PCM connector terminal A40 and body ground.
Is there continuity?
YES -
Go to step 20.
NO -
Repair open in the wire between the PCM(A40) and the PGM-FI subrelay (LAF), then go to step 22.
20. Test the PGM-FI subrelay (LAF) Power Relay Test.
Is the PGM-FI subrelay (LAF) OK?
YES -
Go to step 28.
NO -
Replace the PGM-FI subrelay (LAF), then go to step 22.
21. Replace secondary HO2S (Sensor 2) Secondary HO2S Replacement.
22. Reconnect all connectors.
23. Turn the ignition switch to ON (II).
24. Reset the PCM with the HDS.
25. Do the PCM idle learn procedure PCM Idle Learn Procedure.
26. Check for Pending or Confirmed DTCs with the HDS.
Is DTC P0141 and/or P0161* indicated?
YES -
Check for poor connections or loose terminals at secondary HO2S (Sensor 2), the PGM-FI subrelay (LAF), and the PCM, then go to step 1.
NO -
Go to step 27.
27. Monitor the OBD STATUS for DTC P0141 and/or P0161* in the DTCs MENU with the HDS.
Does the screen indicate PASSED?
YES -
Troubleshooting is complete. If any other Pending or Confirmed DTCs were indicated in step 26, go to the indicated DTC's troubleshooting.�
NO -
If the screen indicates FAILED, check for poor connections or loose terminals at secondary HO2S (Sensor 2), the PGM-FI subrelay (LAF), and the PCM, then go to step 1. If the screen indicates NOT COMPLETED, keep idling until a result comes on.
28. Reconnect all connectors.
29. Update the PCM if it does not have the latest software PCM Update, or substitute a known-good PCM Initial Inspection and Diagnostic Overview.
30. Check for Pending or Confirmed DTCs with the HDS.
Is DTC P0141 and/or P0161* indicated?
YES -
Check for poor connections or loose terminals at secondary HO2S (Sensor 2), the PGM-FI subrelay (LAF), and the PCM. If the PCM was updated, substitute a known-good PCM Initial Inspection and Diagnostic Overview, then recheck. If the PCM was substituted, go to step 1.
NO -
Go to step 31.
31. Monitor the OBD STATUS for DTC P0141 and/or P0161* in the DTCs MENU with the HDS.
Does the screen indicate PASSED?
YES -
If the PCM was updated, troubleshooting is complete. If the PCM was substituted, replace the original PCM Service and Repair. If any other Pending or Confirmed DTCs were indicated in step 30, go to the indicated DTC's troubleshooting.�
NO -
If the screen indicates FAILED, check for poor connections or loose terminals at secondary HO2S (Sensor 2), the PGM-FI subrelay (LAF), and the PCM. If the PCM was updated, substitute a known-good PCM Initial Inspection and Diagnostic Overview, then recheck. If the PCM was substituted, go to step 1. If the screen indicates NOT COMPLETED, keep idling until a result comes on.